Excerpt from: http://vista.cira.colostate.edu/TSS/Results/Emissions.aspx

Emissions M ethods : Wild and Prescribed Fire Emissions

Fire Emissions

Fire emissions data for SMOKE have traditionally been represented as county

- level area

- source inventories that were placed in only the first vertical model layer. T he representa tion of fire emissions for air quality modeling was enhanced by preparing the inventory data as point sources with specific latitude

- longitude coordinates for each fire centroid and pre

- computed plume rise parameters that were derived from individual fire characteristics. These new inventories consist of annual, daily , and hourly IDA

- formatted emissions inventory files and ancillary data for allocating the inventories in space, time, and to the Carbon Bond

- IV chemistry mechanism used in CMAQ and CAMx. The development of the fire emissions inventory is described in this section.

Source Categories

The fire emission inventories developed for the WRAP modeling efforts were organized into the following individual categories:

 Wildfires

 Agricultural fires

 Wildland fire use

 Natural prescribed

 Anthropogenic prescribed

 Non

- F ederal rangeland fires

 non

- WRAP fires

For the non

- WRAP fire emissions inventory, most of the data were modeled as area sources, with the exception of fire emissions for Canada, which were treated as elevated point sources.

The development of the fire emi ssion inventory is described below. The discussion focuses on the development of the 2002 Base inventory; emissions modeling for the 2002 Planning inventory and the 2018 base year inventory use the same processing approach. Variations to the modeling app roach and specific revisions and enhancements incorporated into the final modeling versions of the inventories have been described previously (refer to the Emission Overview Documentation). Specific revisions are noted with respect to data sources and sou rce categories for the Plan02 and Base18 emissions inventories.Data sources

For the fire inventories in Base02 inventory

, a ctual 2002 data were used as developed by the RPOs for the U.S., version 2 of the year 2000 Canadian inventory, and actual 2002 data for Ontario, Canada. There were no fire emissions in the BRAVO 1999 Mexico inventories, so Mexican fires were not included in the Base02 inventories . The inventories used consisted of both area

- and point

- source data for the U.S. and Canada. Air Scien ces provided the WRAP inventories divided among six different fire categories: wildfires, agricultural fires, wildland fire use, natural prescribed, anthropogenic prescribed, and non

- Federal rangeland fires (Air Sciences, Inc., 2005). These inventories con sisted of annual, daily, and hourly IDA

- formatted files with information on daily emissions totals and hourly plume characteristics for each fire. S imilar point source fire inventories for the VISTAS states were received from Alpine Geophysics (Stella, 200 5). In addition, county

- level fire inventories represented as area sources for the VISTAS and CENRAP states were also included

. M onthly temporal profiles received from Alpine Geophysics were used to distribute these annual inventories throughout the year. The area source inventories for the rest of the RPOs and Canada also contained fire emissions that were not distributed separately. T hese sources were modeled with the rest of the stationary

- area

- source sector. Finally, a 2002 fire inventory for Ontario, Canada was received from MANE

- VU and formatted to take advantage of the SMOKE fire plume rise algorithm (Pouliot et al., 2005).

For the development of the Plan02 inventories, th e RMC received corrected U.S. data for only the updated portions of the Base02 inventories. T he previous inventory data for the affected
states were removed from the files used in the Base02 modeling and combined the remaining data with the updated information to build revised Base02 inventories. T he resulting dataset was used to de velop the Plan02 inventory. This substitution of only the revised portions of the inventories was a general approach applied to several emissions sectors. M ore specific approaches were also developed for preparing the Plan02 fire inventories as described below.

Air Sciences, Inc., provided annual Baseline Phase III fire inventories for each of the five fire categories (wildfires, agricultural fires, prescribed fires, non

- Federal rangeland prescribed fires, and wildland fire use) as three

- file sets for eac h category. Consistent with the fire inventories for Phases I and II, each fire category consisted of an annual IDA file with physical fire event information, a daily IDA file with daily emis sions by criteria pollutant, and an hourly IDA file with hourly pre

- computed plume rise values. Upon receiving these data, the annual inventories are split into monthly files to avoid computer memory problems related to processing very large inventories with SMOKE. A dditional information on the develo pment of these fir e inventories is available in WRAP

- FEJF (2006).

Baseline fire emission inventories for 2018 (Base18a) for WRAP, CENRAP, and VISTAS were held constant at Plan02 emission levels. For the 2018b inventory, a number of revisions were incorporated as follows:

 T he WRAP inventories for prescribed and agricultural fires were updated and errors corrected in the application of temporal and speciation profiles for non

- Federal rangeland prescribed fires.

 Air Sciences , Inc. provided revisions to the Phase III prescri bed and agricultural fire inventories to estimate the emissions reductions from applying fire emissions reductiontechniques (ERTs) to controllable fire emissions (Randall, 2006). They b ased the revised

emissions on the same data that the RMC used in case Plan02b to illustrate the changes that resulted from controlling prescribed and ag ricultural fire s between the Plan02b and Base18 b emission scenarios

.

 T he temporal and speciation profiles applied to the non

- Federal rangeland prescribed fires
were correcte d

. By not adding the SCC for this source to the input cross

- reference files in the Plan02 and Base18a inventories , default temporal and speciation profiles were mistakenly applied to these emissions. T he appropriate cross

- reference for this source were ad ded to the SMOKE input files in case Base18b.

Emissions processing

SMOKE is instrumented to distribute point

- source

- formatted fire inventories to the vertical model layers either by using a pre

- computed plume rise approach or by computing the plume rise dynamically using actual 2002 meteorology. B oth approaches for modeling point source fire emissions were applied for the Base02 inventories . For the pre

- computed plume rise approach, SMOKE reads an annual inventory file with information on fire locations, a daily inventory file with daily emission totals for each fire, and an hourly inventory file with hourly plume bottom, plume top, and layer 1 fractions for each fire. SMOKE uses this information to locate the fires on the horizontal model grid and to dist ribute the plume of each fire vertically to the model layers. Because some of these fires have plumes that reach the model top, the number of emissions layers for processing these inventories are set to the full 19 layers of the meteorology. T his approach was applied to the point

- source fires for the WRAP and VISTAS regions.

The alternative plume rise approach uses information on fuel loading and the heat flux of the fires to distribute the fires vertically to the model layers. The data are provided to SMOK E in the form of an annual inventory with information on fire locations and a daily inventory with daily emission totals for each fire, daily heat flux, and daily fuel loading. T his approach to the point source fires was applied for Ontario, Canada.

All o f the point

- source fires used diurnal temporal profiles and speciation profiles for VOC and PM 2.5 developed by Air Sciences during the preliminary 2002 modeling (Tonnesen et al., 2005).

For the area source fires outside of the WRAP region, including Canad a, monthly temporal profiles developed by VISTAS were applied.. While these profiles appear to be an improvement over the EPA defaults, they are specific to the VISTAS region and will misrepresent the seasonality of the fires in other regions of the modeli ng domain. Flat weekly temporal profiles, and the diurnal profiles developed by Air Sciences were also used in the fire emissions modeling. In addition, the forestland spatial surrogates were used to distribute these county level (province level for Canad a) data to the model grid. Using spatial surrogates to locate fires is a crude approach that results in the artificial smearing of the emissions over too large an area. Both of these issues can be remedied by moving to a point source approach for represent ing these fires, similar to the approach used by Air Sciences for preparing the WRAP fire inventories.The RMC discovered several errors with the WRAP Phase II inventories. Some of these errors

were fixed with corrections made by the RMC with guidance fro m Air Sciences, and others will be addressed by Air Sciences in Phase III of the 2002 WRAP fire inventories. The errors identified, with corrections, were as follows:

 Missing or malformed dates in several agricultural burning events in CA. These events

we re intended to be dropped and were ultimately deleted from the inventories by the RMC.

 Missing dates in several prescribed burning events in AZ. These records were corrected by Air Sciences and redistributed to the RMC.

 Inconsistencies between the records in the hourly and annual inventory files for several agricultural burning events in CA. These records were corrected by Air Sciences and redistributed to the RMC.

The quality assurance of the fire emissions followed the WRAP emissions modeling QA protocol (Adelman, 2004) and a suite of graphical summaries. Tabulated summaries of the input data and SMOKE script settings were used to document the data and configuration of SMOKE. The graphical QA summaries include, for all emissions output species, daily tim e

- series plots, annual time

- series plots, and daily vertical profiles. These QA graphics for the 2002 inventories are

a vailable at http://pah.cert.ucr.edu/aqm/308/QA_base02a36.p lots/allf/plots/

.

Gridded Fire Emission Inventory Summaries

Summaries of the gridded fire source emissions for the Base02b, Plan02c and Base18b inventories by state and county, annual and seasonal periods, can be found on the TSS at: http://vista.cira.colostate.edu/tss/Results/Emissions.aspx

.

References

Adelman, Z. 2004: Quality Assurance Protocol

– WRAP RMC Emissions Modeling with SMOKE, Prepared for the WRAP Modeling Forum by the WRAP Regional Modeling Center, Riverside, CA. Air Sciences, Inc., 2005: 2002 Fire Emission Inventory for the WRAP Region

– Phase II, Prepared for the Western Governors Association/WRAP by Air Sciences, Inc., Denver, CO. Pouliot, G., T. Pierce, W. B enjey, S.M. O’Neill, and S.A. Ferguson, 2005: Wildfire Emissions Modeling: Integrating Blue Sky and SMOKE, in Proceedings of the 14th Annual Emissions Inventory Conference, Atlanta, GA. Randall, D., 2006: Technical Memorandum: Fire Emissions Inventory

– P hase III Base

- Control Case, Prepared for Western Regional Air Partnership Fire Emissions Joint Forum by Dave Randall, Air Sciences, Inc., April 28, 2006. Tonnesen, G. et al., 2005: Final Report for the WRAP RMC for the Project Period March 1, 2004 through February 28, 2005, Prepared for the Western Governors Association by ENVIRON International Corporation, Novato, CA. http://pah.cert.ucr.edu/aqm/308/ppt_f iles/emissions/nh3/Volume_I_FinalReport.3

- 07.pdfWRAP

- FEJF (WRAP

- Fire Emissions Joint Forum). 2006. WRAP Phase III & IV Fire Emission

Inventories for the 2000

- 04 Baseline Period and 2018 Project Year. Western Governors Association

– wrapair.org website. ( http://www.wrapair.org/forums/fejf/tasks/FEJFtask7Phase3

- 4.html ).